A drive axle assembly for a rear wheel drive vehicle, for example, typically includes an axle housing, a pair of axles for driving wheels located at the outer ends of the housing, and a differential gear arrangement mounted centrally in the housing for driving the axles. The inner ends of the axles are typically splined to drive gears in the differential gear assembly, whereas the outer ends are rotatably supported by wheel bearings located at the ends of the axle housing. Until recently the wheel bearings were usually press-fitted onto the axles and bearing retainer plates mounted at the extreme outer ends of the housing clamped the bearings to the housing and hence secured the axles in position.
At least one automobile manufacturer presently uses locking elements within the differential assembly itself to maintain the axles within the axle housing instead of axle retainer plates mounted at the ends of the housing. In the rear axle assemblies currently employing internal locking elements for retaining the axles, the differential gearing mounted within the axle housing is a conventional bevel gear differential. As is conventional in this type of differential, a ring gear rotates a differential case which mounts four interengaged bevel gears that rotate about two mutually orthogonal axes. One axis is defined by the axles to which two of the bevel gears are drivingly coupled. Generally these "axle drive" gears include splined bores that engage mating splines formed on the axle ends; this one axis is normally coincident with the rotational axis of the ring gear. The remaining two bevel gears are generally termed "spider" gears. These gears rotate on a common axis usually defined by a common shaft mounted in the case and intersecting the first axis at 90.degree.. The spiders "differentiate" torque between the axle drive gears.
Each axle drive gear includes an annular recess adjacent and coaxial with the splined bore. Because the recess is larger than the bore, a shoulder is defined therebetween. The end of each axle includes a groove for receiving a locking "C-ring". To couple the axles to the axle assembly, each axle is first inserted, inner end first, from the respective outer ends of the housing, through the associated axle gears, until the locking grooves extend beyond the associated drive gears. C-rings are then inserted into the grooves and the axles moved outwardly so that the C-rings enter the recesses formed in the axle drive gears. The recesses are sized to prevent displacement of the C-rings from the axle ends.
The shaft for the spider gears, when positioned, extends between the axle ends and intersects the axis of the axles. By critically sizing the diameter of the shaft as well as the distance between the locking groove and end face on each axle end, the shaft in effect maintains the assembled position of the axles and further provides a thrust surface for the axles.
The installation of a differential mechanism, other than a bevel gear differential, in an axle housing employing this type of arrangement for retaining the axles within the housing presents some difficulty, if the differential to be installed does not include a shaft or a pin disposed along a line that intersects the axis of the axles. An example of one such differential is illustrated in U.S. Pat. No. 2,859,641 to Gleasman. The differential mechanism disclosed in this Gleasman patent is termed a "cross-axis compound planetary gear complex" and includes worm gears rotatably coupled to each axle and balancing gear complexes rotatably supported by the differential case for transferring torque between the axle gears. The gear complexes are mounted in pairs and each complex rotates on an axis of rotation that is substantially tangential to the pitch of its associated axle drive gear. In the differential mechanism disclosed in this Gleasman patent, the axle gears include inner end faces positioned in confronting alignment with a thrust bearing intermediate the faces. It is considered unfeasible to provide a shaft between the axle drive gears to act as a thrust and locating surface for the ends of the axles. Nevertheless, it has been considered desirable to find a method for mounting this type of differential in an axle housing of the type described above.